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1.
Presented are results of Perseid 1993 meteor shower from radar observation at Ondejov observatory. Investigation of the shower activity profiles in four echo duration intervals proved the position of dominant peak at solar longitude L = 138.°8±0.°05 (epoch 1950.0) followed by series of secondary maxima positions of which depend on examined echo duration class. Extremely low value of the mass distribution indexs = 1.27 ± 0.01 near the maximum activity peak associated with high proportion of fragmenting particles leads to the suggestion that meteor particles concentrated in this filament are younger than those which form the other parts of the stream.  相似文献   

2.
Hari Om Vats 《Solar physics》1992,138(2):379-386
Characteristics of flare-associated high-speed solar plasma streams are investigated using measurements from space probes and Earth-orbiting spacecraft for the period 1964–1982. The maximum observed velocity (V m) of these streams range from 400 to 850 km s–1} with peak probability for 600 km s–1}. These remain for the period of 1–10 days with the peak occurrence 3 days. The difference between the pre-stream velocity (V 0) and the maximum velocity (V m) of any high-speed stream serves as the measure of its intensity. For about 60% of the flare associated streams, (V m-V 0) is well in excess of 200 km s–1} and in some cases becomes as large as 450 km s–1}. The yearly percentage occurrence, total duration and the product of mean (V m - V 0) with total duration of the high-speed streams during the year correlates well with solar activity, e.g., maximum during high solar activity period and minimum during low solar activity. The study suggests that presence of sunspots plays a significant role in the generation of flare associated high-speed solar streams.  相似文献   

3.
Spectroheliograms in the L Mg xii line and in the Mg xi resonance (R) 1s 21 S 0-1s2p 1 P 1 line, intercombination (I) 1s 21 S 0-1s2p 3 P 1,2, line, and the forbidden (F) 1s 21 S 0-1s2s 3 S 1 line, have been obtained.Two Bragg crystal spectrometers were used mounted with mechanical collimators to obtain a spatial resolution of 1 × 3. The apparatus was launched on a sounding rocket on July 2nd, 1971. A particularly thorough study was made of the brightest active region (MC 11402).Variations in the F to I Mg xi line intensity ratio from one point to another in the active region did not reveal the presence of high electron densities.The observed intensities of the Mg xi R line, Mg xii L line and Mg x 1s 22s 2 S 1/2-1s2p 1 P 2s × × 2 P11/2, 3/2 S line are not well explained by an isothermal model. Good agreement between computed and observed intensities is obtained using the non-isothermal model proposed here.  相似文献   

4.
We consider the dynamics of a test particle co-orbital with a satellite of mass m s which revolves around a planet of mass M 0 m s with a mean motion n s and semi-major axis a s. We study the long term evolution of the particle motion under slow variations of (1) the mass of the primary, M 0, (2) the mass of the satellite, m s and (3) the specific angular momentum of the satellite J s. The particle is not restricted to small harmonic oscillations near L 4 or L 5, and may have any libration amplitude on tadpole or horseshoe orbits. In a first step, no torque is applied to the particle, so that its motion is described by a Hamiltonian with slowly varying parameters. We show that the torque applied to the satellite, as measured by s = js/(n s J s) induces an distortion of the phase space which is entirely described by an asymmetry coefficient = s/, where = m s/M. The adiabatic invariance of action implies furthermore that the long term evolution of the particle co-orbital motion depends only on the variation of m s a s with time. Applying a constant torque to the particle, as measured by s = js/(n s J p) is then merely equivalent to replacing = s/ by = (s – p)/. However, if the torque acting on the particle exhibits a radial gradient, then the action is no more conserved and the evolution of the particle orbit is no more controlled by m s a s only. We show that even mild torque gradients can dominate the orbital evolution of the particle, and eventually decide whether the latter will be pulled towards the stable equilibrium points L 4 or L 5, or driven away from them. Finally, we show that when the co-orbital bodies are two satellites with comparable masses m 1 and m 2, we can reduce the problem to that of a test particle co-orbital with a satellite of mass m 1 + m 2. This new problem has then parameters varying at rates which are combinations, with appropriate coefficients, of the changes suffered by each satellite.  相似文献   

5.
In the region of the formation of weak and medium-strong lines, the microturbulence increases with height (V ver=0.7–0.9 km s-1, V hor= 1.1–1.5 km s-1), the macroturbulence decreases (V ver=1.6–1.4 km s-1, V hor= 2.4–1.5 km s-1), and the total velocity field (vertical component) is depth-independent (1.7 km s-1). The empirical damping constants for Fe, Ti, Cr, Ni lines are equal 1.36, 1.76, 1.66, 1.66, respectively. The correlation length (the Kubo-Anderson process has been used) in the solar photosphere is 520–550 km.  相似文献   

6.
Tu  C.-Y.  Marsch  E. 《Solar physics》1997,171(2):363-391
A model of the solar corona and wind is developed which includes for the first time the heating and acceleration effects of high-frequency Alfvén waves in the frequency range between 1 Hz and 1 kHz. The waves are assumed to be generated by the small-scale magnetic activity in the chromospheric network. The wave dissipation near the gyro-frequency, which decreases with increasing solar distance, leads to strong coronal heating. The resulting heating function is different from other artificial heating functions used in previous model calculations. The associated thermal pressure-gradient force and wave pressure-gradient force together can accelerate the wind to high velocities, such as those observed by Helios and Ulysses. Classical Coulomb heat conduction is also considered and turns out to play a role in shaping the temperature profiles of the heated protons. The time-dependent two-fluid (electrons and protons) model equations and the time-dependent wave-spectrum equation are numerically integrated versus solar distance out to about 0.3 AU. The solutions finally converge and settle on time-stationary profiles which are discussed in detail. The model computations can be made to fit the observed density profiles of a polar coronal hole and polar plume with the sonic point occurring at 2.4 R and 3.2 R , respectively. The solar wind speeds obtained at 63 R are 740 km s-1 and 540 km s-1; the mass flux is 2.1 and 2.2 × 108 cm-2 s-1 (normalized to 1 AU), respectively. The proton temperature increases from a value of 4 × 105 K at the lower boundary to 2 × 106 K in the corona near 2 R .  相似文献   

7.
S. Koutchmy 《Solar physics》1972,24(2):373-384
A Hydrodynamical Study of the Large NE Coronal Streamer Observed during the 7th March Eclipse. The photometry of the large coronal streamer located on the N-E limb of the Sun observed on the 7th March 1970 in Mexico has been performed using compensated plates in unpolarized light as well as in tangentially and radially polarized light. The measured polarizations permit us to locate the streamer in space using a generally used method. The density distribution in the core of the streamer and for r > 1.5 R is given as well as the half-widths of the density distribution perpendicular to the axis of the streamer. Densities n(r) in the 1(R ) < r < 1.5(R ) region are obtained assuming hydrostatic equilibrium (4) for 1.5 < r < 2.The axial values of n(r) are given which agree with those of others models. The values of parameters for the model given are tabulated.The variation of the expansion velocity has been derived from the hydrodynamical continuity equation. This velocity becomes supersonic [v > 150(km s–1)] above the height of minimum cross section of the streamer, r = 3.5 (R ). This result is verified by a simple calculation based on the observed curvature of the streamer's stalk. The velocity corresponding to the garden hose effect considered has a lower value equal to 60(km s–1). The radial distribution of the expansion velocity is shown. Our model allows us to extrapolate in order to obtain the value of v(r) at the Sun's surface. This value, v 0.07 (km s–1) can be compared with the value of the differential rotation velocity of the foot of the streamer. The values of the corpuscular flux of the streamer are calculated [F=2.4 × 1034( s-1] and agree with the value of the flux corresponding to the density enhancements of the solar wind, measured in situ. This shows the importance of large streamers for the coronal expansion processus.  相似文献   

8.
A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation ( 50 TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each burst are presented for seven GRBs located with zenith angles < 20°. A 4.3 excess over background was observed between 10 and 20 minutes following the onset of a GRB on 11 May 1991. The confidence level that this is due to a real effect and not a background fluctuation is 99.8%. If this effect is real then cosmological models are excluded for this burst because of absorption of UHE gamma rays by the intergalactic radiation fields.  相似文献   

9.
The sidereal rotation rate of the high-latitude solar regions is examined using long-lived photospheric polar faculae. The observations were carried out with the photoheliograph of Kislovodsk Mountain Station of the Pulkovo Observatory from 1982 to 1986. The following facts have been established: (a) There is a differential rotation of the polar faculae close to the maximum of solar activity, while the amount of latitude gradient of solar rotation decreases towards the sunspot minimum; (b) small differences of rotation in the northern and southern hemispheres of the Sun are observed; (c) some deviations of differential rotation curves constructed for each Carrington rotation from the mean curve of differential rotation are revealed. The total amplitude of the maximum positive and negative excesses is about 40–50 m s–1. The positive surplus velocities of solar rotation (the amplitude of which is about 20–25 m s–1) move in the form of a wave from heliographic latitudes 40° with a velocity of 1.6 m s–1. The latitude width of this flow is B 15°. This wave of abnormally high velocity starts in the year of minimum solar activity and reaches the pole 11 years later. The picture is symmetrical relative to the equator.  相似文献   

10.
It is shown that the brightness of the spiral galactic nuclei at 10 depends on the Byurakan type of galaxies: the brightness is higher in the case of galaxies of types 5, 2s, 4, and 2 with optical signs of activity in comparison with galaxies of types 3 and 1 without optical signs of activity. The noted difference is larger when nonstellar emission at 10 is considered. The obtained results confirm conclusions made earlier on the activity of the nuclei of galaxies of types 5, 2s, 4, and 2.  相似文献   

11.
The activity of the Leonid shower in the years 1944–1953 was derived from visual records obtained at the Skalnaté Pleso Observatory, using the zenithal exponent = 1.47 in the reduction factor cos z R.  相似文献   

12.
The variation in intensity of the solar X-ray resonance (1s 2 1 S 0 - 1s2p 1 P 1), intercombination (1s 2 1 S 0 - 1s2p 3 P 1), and forbidden (1s2 1 S 0 - 1s2s 3 P 1) lines of helium-like Ovii with 2800 MHz solar radio flux is presented for three solar rotations. A high correlation (r 0.80) exists between the intensities of all three X-ray lines and the 2800 MHz solar flux. The ratio of the forbidden to the intercombination line intensities is found to be essentially independent of long term solar activity. This ratio is used to determine upper limits on the coronal electron density and to make inferences concerning the change in density with solar activity.  相似文献   

13.
BUSS observations of the profiles of two well observed spectral lines in the ultraviolet spectrum of CMi (Procyon; F5 IV–V) are analysed with a Fourier transform method in order to determine values of various parameters of the velocity field of the upper photosphere. We find a microturbulent line-of-sight velocity componentL = 0.9 ± 0.4 km s–1, a macroturbulent velocity componentL M = 5.3 ± 0.2 km s–1, and a rotational velocity componentv R sini=10.0±1.2 km s–1. In these calculations a single-moded sinusoidal isotropic macroturbulent velocity function was assumed. The result appears to be sensitive to the assumed shape of the macroturbulence function: for an assumed Gaussian shape the observations can be described withv R sini=4 km s–1 andL M = 11.6 ± 2.7 km s–1. A comparison is made with other results and theoretical predictions.  相似文献   

14.
The law of rotation as well as the corresponding meridional circulations in the hydrogen convection zone (HCZ) are investigated by solving numerically the time independent Navier-Stokes equations. The HCZ is assumed to be a spherical layer of fluid with constant density and viscosity. It is assumed further that the viscosity is caused by unisotropic turbulent motions.The results show differential rotation together with circulations. The detailed behaviour depends on a parameters characterizing the nonisotropic friction and on the kinematic viscosityv. If the friction is larger in radial direction than in lateral directions (0 s < 1) the poles rotate faster than the equator and the circulation rises at the equator and falls at the poles; if friction is smaller in radial direction (s > 1) the equator rotates faster and the sense of the circulation is reversed. The differential rotation observed at the solar surface is obtained for the values = 1.2.For small values ofv the angular velocity is constant on cylindrical surfaces, for large values ofv it is constant on spherical surfaces. The solar law of rotation turns out to be very close to the first case.Based on the author's Thesis in Göttingen.  相似文献   

15.
The energy differences between 1s 22p 1s2p3p transitions and the corresponding 1s 2 1s3p resonances are expressed by means of a polynomial function of the atomic number. The agreement with experimental data from lithium to potassium is very good. Interpolated values for nitrogen to sodium and argon as well as extrapolation for calcium are reported.  相似文献   

16.
The Bragg-type, flat ADP crystal spectrometer, launched on board the INTERCOSMOS 16 satellite has been used for measurements of the X-ray spectra emitted from solar active region plasmas. During the period of the instrument operation (August–September, 1976) only a few active regions were present on the Sun (minimum of the solar activity). About 60 spectra have been registered. In the present paper using a spectrum averaged over 20 scans, we measured the wavelengths corresponding to the statistically significant spectral features seen in this spectrum in the wavelength range 9.14–9.33 Å. By comparison with the calculated line wavelengths and intensities predicted in the framework of the thermal model of the average active region, we performed the identification of these features. Besides rather prominent resonance, intercombination, and forbidden lines of the He-like ion Mg xi, it was possible to identify the satellite lines which correspond to 1s 2 nl - 1s2p nl transitions from the states with n = 2, 3, and 4. The present paper is the first in a series dealing with the INTERCOSMOS 16 Mg xi spectra.  相似文献   

17.
Results are presented of an investigation of solar flare X-ray spectra in the region 1.70–1.95 Å, obtained aboard the Intercosmos-4 satellite during the maximum of solar activity (October–November, 1970). With the use of 6 high resolution spectra in the region 1.85–1.87 Å the identification of lines due to 18 transitions of 2p 1s type, consisting of the resonance, intercombination and forbidden Fe xxv ion lines and the satellite Fe xxiv lines has been performed. With the use of the recent laboratory data the averaged wavelengths of the lines were obtained confirming the theoretically calculated ones with an accuracy about ± 0.0004 Å. A variable Doppler shift of the Fe xxv resonance lines was observed for the flare of November 16, 1970, which points to hot plasma motions with velocities up to 400 km s-1.  相似文献   

18.
《Astroparticle Physics》2009,32(2):89-99
Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ∝P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a 10% seasonal modulation and 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.  相似文献   

19.
We measure the separation velocity of opposite poles from 24 new bipoles on the Sun. We find that the measured velocities range from about 0.2 to 1 km s–1. The fluxes of the bipoles range over more than two orders of magnitude, and the mean field strength and the sizes range over one order of magnitude. The measured separation velocity is not correlated with the flux and the mean field strength of the bipole. The separation velocity predicted by the present theory of magnetic buoyancy is between 7.4Ba –1/4 cot and 13 cot km s–1, where is the elevation angle of the flux tube at the photosphere (see Figure 9), B is the mean field strength, and a is the radius of the observed bipole. The rising velocity of the top of flux tubes predicted by the theory of magnetic buoyancy is between 3.7Ba –1/4 and 6.5 km s–1. The predicted separation velocity is about one order of magnitude higher than those measured, or else the flux tubes are almost vertical at the photosphere. There is no correlation between the measured separation velocity and the theoretical value, 7.4Ba –1/4. The predicted rising velocity is also higher than the vertical velocity near the line of inversion in emerging flux regions observed by other authors.  相似文献   

20.
Paul A. Wiegert  Martin Houde 《Icarus》2008,194(2):843-846
Asteroid 3200 Phaethon resembles a comet in some ways, including a highly-eccentric orbit (e∼0.89) and a strong associated meteor shower (the Geminids). Yet this object has never been observed to exhibit any cometary activity, i.e., gas production. We observed 3200 Phaethon with the Caltech Submillimeter Observatory on two occasions, once while it was near its closest approach to Earth as it neared perihelion, and another while it was further from Earth post-perihelion. Observations of the J=2→1 and J=3→2 rotational transitions of 12CO, typically strong lines in comets and indicative of gas production, yielded no detection. Upper limits on the 12CO production of 1.8×1028 and for Phaethon were determined on these two occasions.  相似文献   

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